Struct AgentConfig 

#[non_exhaustive]
pub struct AgentConfig<Tools = NoTools, Schema = NoSchema> {
    pub system_prompt: Option<String>,
    pub prompt: String,
    pub model: String,
    pub allowed_tools: Vec<String>,
    pub max_turns: Option<u32>,
    pub max_budget_usd: Option<f64>,
    pub working_dir: Option<String>,
    pub mcp_config: Option<String>,
    pub permission_mode: PermissionMode,
    pub json_schema: Option<String>,
    pub resume_session_id: Option<String>,
    pub verbose: bool,
    /* private fields */
}

Serializable configuration passed to an AgentProvider for a single invocation.

Built by Agent::run from the builder state. Provider implementations translate these fields into whatever format the underlying backend expects.

Typestate: tools vs structured output

Claude CLI has a known bug where combining --json-schema with --allowedTools always returns structured_output: null. To prevent this at compile time, allow_tool and output / output_schema_raw are mutually exclusive: using one removes the other from the available API.

use ironflow_core::provider::AgentConfig;

// OK: tools only
let _ = AgentConfig::new("search").allow_tool("WebSearch");

// OK: structured output only
let _ = AgentConfig::new("classify").output_schema_raw(r#"{"type":"object"}"#);

use ironflow_core::provider::AgentConfig;
// COMPILE ERROR: cannot add tools after setting structured output
let _ = AgentConfig::new("x").output_schema_raw("{}").allow_tool("Read");

use ironflow_core::provider::AgentConfig;
// COMPILE ERROR: cannot set structured output after adding tools
let _ = AgentConfig::new("x").allow_tool("Read").output_schema_raw("{}");

Workaround: split the work into two steps – one agent with tools to gather data, then a second agent with .output::<T>() to structure the result.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

system_prompt: Option<String>

Optional system prompt that sets the agent’s persona or constraints.

prompt: String

The user prompt - the main instruction to the agent.

model: String

Which model to use for this invocation.

Accepts any string. Use Model constants for well-known Claude models (e.g. Model::SONNET), or pass a custom identifier for other providers.

allowed_tools: Vec<String>

Allowlist of tool names the agent may invoke (empty = provider default).

max_turns: Option<u32>

Maximum number of agentic turns before the provider should stop.

max_budget_usd: Option<f64>

Maximum spend in USD for this single invocation.

working_dir: Option<String>

Working directory for the agent process.

mcp_config: Option<String>

Path to an MCP server configuration file.

permission_mode: PermissionMode

Permission mode controlling how the agent handles tool-use approvals.

json_schema: Option<String>

Optional JSON Schema string. When set, the provider should request structured (typed) output from the model.

resume_session_id: Option<String>

Optional session ID to resume a previous conversation.

When set, the provider should continue the conversation from the specified session rather than starting a new one.

verbose: bool

Enable verbose/debug mode to capture the full conversation trace.

When true, the provider uses streaming output (stream-json) to record every assistant message and tool call. The resulting AgentOutput::debug_messages field will contain the conversation trace for inspection.

Implementations

impl AgentConfig

pub fn new(prompt: &str) -> Self

Create an AgentConfig with required fields and defaults for the rest.

impl<Tools, Schema> AgentConfig<Tools, Schema>

pub fn system_prompt(self, prompt: &str) -> Self

Set the system prompt.

pub fn model(self, model: &str) -> Self

Set the model name.

pub fn max_budget_usd(self, budget: f64) -> Self

Set the maximum budget in USD.

pub fn max_turns(self, turns: u32) -> Self

Set the maximum number of turns.

pub fn working_dir(self, dir: &str) -> Self

Set the working directory.

pub fn permission_mode(self, mode: PermissionMode) -> Self

Set the permission mode.

pub fn verbose(self, enabled: bool) -> Self

Enable verbose/debug mode.

pub fn mcp_config(self, config: &str) -> Self

Set the MCP server configuration file path.

pub fn resume(self, session_id: &str) -> Self

Set a session ID to resume a previous conversation.

impl<Tools> AgentConfig<Tools, NoSchema>

pub fn allow_tool(self, tool: &str) -> AgentConfig<WithTools, NoSchema>

Add an allowed tool.

Can be called multiple times to allow several tools. Returns an AgentConfig<WithTools, NoSchema>, which cannot call output or output_schema_raw.

This restriction exists because Claude CLI has a known bug where --json-schema combined with --allowedTools always returns structured_output: null.

Workaround: use two sequential agent steps – one with tools to gather data, then one with .output::<T>() to structure the result.

Examples

use ironflow_core::provider::AgentConfig;

let config = AgentConfig::new("search the web")
    .allow_tool("WebSearch")
    .allow_tool("WebFetch");

use ironflow_core::provider::AgentConfig;
// ERROR: cannot set structured output after adding tools
let _ = AgentConfig::new("x")
    .allow_tool("Read")
    .output_schema_raw(r#"{"type":"object"}"#);

impl<Schema> AgentConfig<NoTools, Schema>

pub fn output<T: JsonSchema>(self) -> AgentConfig<NoTools, WithSchema>

Set structured output from a Rust type implementing JsonSchema.

The schema is serialized once at build time. When set, the provider will request typed output conforming to this schema.

Important: structured output requires max_turns >= 2.

Returns an AgentConfig<NoTools, WithSchema>, which cannot call allow_tool.

This restriction exists because Claude CLI has a known bug where --json-schema combined with --allowedTools always returns structured_output: null.

Workaround: use two sequential agent steps – one with tools to gather data, then one with .output::<T>() to structure the result.

Known limitations of Claude CLI structured output

The Claude CLI does not guarantee strict schema conformance for structured output. The following upstream bugs affect the behavior:

• Schema flattening (anthropics/claude-agent-sdk-python#502): a schema like {"type":"object","properties":{"items":{"type":"array",...}}} may return a bare array instead of the wrapper object. The CLI non-deterministically flattens schemas with a single array field.
• Non-deterministic wrapping (anthropics/claude-agent-sdk-python#374): the same prompt can produce differently wrapped output across runs.
• No conformance guarantee (anthropics/claude-code#9058): the CLI does not validate output against the provided JSON schema.

Because of these bugs, ironflow’s provider layer applies multiple fallback strategies when extracting the structured value (see extract_structured_value).

Examples

use ironflow_core::provider::AgentConfig;
use schemars::JsonSchema;

#[derive(serde::Deserialize, JsonSchema)]
struct Labels { labels: Vec<String> }

let config = AgentConfig::new("classify this text")
    .output::<Labels>();

use ironflow_core::provider::AgentConfig;
use schemars::JsonSchema;
#[derive(serde::Deserialize, JsonSchema)]
struct Out { x: i32 }
// ERROR: cannot add tools after setting structured output
let _ = AgentConfig::new("x").output::<Out>().allow_tool("Read");

Panics

Panics if the schema generated by schemars cannot be serialized to JSON. This indicates a bug in the type’s JsonSchema derive, not a recoverable runtime error.

pub fn output_schema_raw(self, schema: &str) -> AgentConfig<NoTools, WithSchema>

Set structured output from a pre-serialized JSON Schema string.

Returns an AgentConfig<NoTools, WithSchema>, which cannot call allow_tool. See output for the rationale and workaround.

Trait Implementations

impl<Tools: Clone, Schema: Clone> Clone for AgentConfig<Tools, Schema>

fn clone(&self) -> AgentConfig<Tools, Schema>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Tools: Debug, Schema: Debug> Debug for AgentConfig<Tools, Schema>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de, Tools, Schema> Deserialize<'de> for AgentConfig<Tools, Schema>

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<AgentConfig<NoTools, WithSchema>> for AgentConfig

fn from(config: AgentConfig<NoTools, WithSchema>) -> Self

Converts to this type from the input type.

impl From<AgentConfig<WithTools>> for AgentConfig

fn from(config: AgentConfig<WithTools, NoSchema>) -> Self

Converts to this type from the input type.

impl<Tools, Schema> Serialize for AgentConfig<Tools, Schema>

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.